CVE-2021-28651
Description
An input validation flaw was found in Squid. This issue could allow a malicious server in collaboration with a trusted client to consume arbitrarily large amounts of memory on the server running Squid. The highest threat from this vulnerability is to system availability.
Statement
This issue has been rated as having a security impact of Moderate. At this stage in their life, Red Hat Enterprise Linux 6 and 7 only accept Important and Critical Security Advisories (RHSAs) and this flaw does not meet these criteria. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata.
Red Hat Satellite does not ship the Squid package, however, does consume it from RHEL 7 repository. Product is not affected by this flaw as squid.conf configuration disables all the http_access fragments except the localhost.
Mitigation
If possible, disable URN processing by adding the following lines in `squid.conf`:
acl URN proto URN
http_access deny URN
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.4 | 7.5 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | Required | None | N/A |
| Scope | Changed | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Acknowledgements
Upstream acknowledges Joshua Rogers (Opera Software) as the original reporter.
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